B‑lines on lung ultrasound: a non‑invasive marker for short‑term outcomes after coronary artery bypass grafting

Abstract Background Postoperative pulmonary complications increase morbidity and mortality after coronary artery bypass grafting (CABG). Lung ultrasound detection of B-lines is an established method to quantify pulmonary congestion, and while B-lines have been studied as predictive markers in heart failure and general critical care settings, their role in predicting outcomes specifically for post-CABG patients remains inadequately defined. This study aimed to evaluate the association between B-lines detected on postoperative lung ultrasound and 30-day mortality and hospital length of stay in patients undergoing isolated CABG. Methods This prospective cohort study was conducted in a single-center intensive care unit between 2023 and 2024. A total of 148 adult patients scheduled for elective CABG were enrolled. Lung ultrasound was performed on postoperative days 1 (POD1) and 3 (POD3) using a standardized 8-zone protocol to quantify B-lines. The primary outcomes were all-cause 30-day mortality, assessed via hospital records and telephone follow-up, and total hospital length of stay. Univariate and multivariate logistic and linear regression analyses were used to identify predictors. Results The mean patient age was 60.15 ± 9.8 years, and 57% were male. Within 30 days, 22 patients (15%) died. In the multivariate logistic regression, the number of B-lines on POD1 was an independent predictor of 30-day mortality (Adjusted Odds Ratio: 1.090, 95% CI: 1.018–1.167, p = 0.013), indicating a 9% increase in the odds of death for each additional B-line. In contrast, the B-line count on POD3 was not significantly associated with mortality. B-line counts on both days were also not associated with hospital length of stay. Instead, higher body mass index (β = 0.22, p = 0.022) and a history of smoking (β = 2.20, p = 0.020) were independently associated with longer hospitalization. Conclusions Early postoperative pulmonary congestion, as quantified by B-lines on POD1 lung ultrasound, is an independent predictor of 30-day mortality after CABG. Routine bedside lung ultrasound on the first day after surgery can serve as a non-invasive tool to stratify high-risk patients, potentially allowing for earlier intervention to optimize fluid status and improve outcomes.